That sounds more complicated. You are stopped of a hill. Your foot is on the brake. Press hard when ready to go, the car beeps, and when you let off the brake it does it roll back and you accelerate up the hill once you apply the gas.
Your suggestion involves using both left and right foot which is not how one drives.
This seems overly complicated. Why not just keep pressing the brake pedal while pressing the accelerator peddle until you can feel the car go forward before releasing the brake pedal.